How much energy we can save ? Energy needed to treat water Average energy use for water treatment drawn from southern California studies is 652 kWh per acre-foot (AF), where one AF = 325,853 gallons. Thermal Energy in Coal The thermal power plants consume about 0.45 kg of coal per kWh. Energy output/fire power plant A typical 500 megawatt coal power plant produces 3.5 billion kWh per year. CO₂ Emission Taking coal to contain 50 percent carbon, which combines with oxygen during burning to form CO₂, we can arrive at 1.83 kg CO₂ for every 1 kg of coal burned.

Structural Analysis
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To calculate the savings, we need to first determine reduction in waste- water generation for given 7 million population of Hongkong, only 1 million people in HK using low flush toilet and low shower head/ 1 million leaky toilet and faucet. Assume all use shower.

Conventional Water fixtures

End-Use

Conventional fixtures

Usage pattern

Population

Daily Usage

Toilets

3.5 gal/flush

4 flushes/per/day

6 million

3.5*4*6 = 84 million gallons

Showers

5 gal/min

5 min/shower

6 million

5*5*6 = 150 million gallons

Faucets

4 gal/min

2.5 min/per/day

6 million

4*2.5*6 = 60 million gallons

Leaks

10% of total use

-

-

0.1*(84+150+60) = 29.4 million gallons

Total

 

 

 

323.4  million gallons

 

Water efficient fixtures

End-Use

Water efficient fixtures

Usage pattern

Population

Daily Usage

Toilets

1.6 gal/flush

4 flushes/per/day

1 million

1.6*4*1 = 6.4 million gallons

Showers

2.5 gal/min

5 min/shower

1 million

2.5*5*1 = 12.5 million gallons

Faucets

2 gal/min

2.5 min/per/day

1 million

2*2.5*1 = 5 million gallons

Leaks

2 % of total use

-

-

0.02*(6.4+12.5+5) = 0.478 million gallons

Total

 

 

 

24.378  million gallons

Per day reduction  in waste-water generation = 323.4 - 24.378

Per day reduction  in waste-water generation = 299.022 million gallons

Total water saving per year in galloon  109143.03 million gallons. (299.022 *365)

 

  1. How much energy we can save?

Calculation of Energy saving

Given that Average energy use for waste-water treatment = 652 KWh per AF for 325,853 gallons

Average energy use for 1-gallon waste-water treatment = 0.002 KWh (652/325,853)

Per day Average energy use for  299.022 million gallons waste-water treatment = 299022000*0.002

Pre day energy saving =598044 KWh

 

  1. How much coal (kg) we can save?

 

Given that thermal power plant consumes about 0.45 kg of coal per KWh

From above step -  Per day  energy saving = 598044 KWh

Per day  coal saving  = 0.45*598044

Per day  coal saving  = 269119.8 kg

 

  1. How much CO2 we can reduce?

Given that 1.83 kg of CO2 is released for every 1 kg of coal burning

From above step -Per day  coal saving  = 269119.8 kg

Per day  reduction in CO2 = 1.83 * 269119.8

Per day  reduction in CO2 = 492489.234 kg

 

  1. How many African children (1 Litres/kid/day) we can support?

Per day reduction in waste-water generation = 299.022 million gallons

Noted that 1 gallons = 3.785 Litres

299.022 million gallons  = 299.022*3.785 million Litres

Per day reduction in waste-water generation = 1131.8 million Litres

Given rate of consumption of African children = 1 Litres/kid/day

Number of African children that can support = 1131.8 million Litres /day 1 Litres/kid/day

Number of African children that can support = 1131.8 million

 

 

TABLE 4.8 Usage Characteristics of Water-Using Fixtures
End-Use
Toilets
Showers
Faucets
Dishwashers
Clothes washers
Leaks
Conventional Fixtures Water-Efficient Fixtures
3.5 gal/flush
5.0 gal/min
4.0 gal/min
14.0 gal/load
55.0 gal/load
10% of total use
1.6 gal/flush
2.5 gal/min
2.0 gal/min
8.5 gal/load
42.0 gal/load
2% of total use
Usage Pattern
4 flushes/pers/day
5 min./shower
2.5 min/pers/day
0.17 loads/pers/day
0.3 loads/pers/day
N/A
% Hot Water
0%
60%
50%
100%
25%
50%
Transcribed Image Text:TABLE 4.8 Usage Characteristics of Water-Using Fixtures End-Use Toilets Showers Faucets Dishwashers Clothes washers Leaks Conventional Fixtures Water-Efficient Fixtures 3.5 gal/flush 5.0 gal/min 4.0 gal/min 14.0 gal/load 55.0 gal/load 10% of total use 1.6 gal/flush 2.5 gal/min 2.0 gal/min 8.5 gal/load 42.0 gal/load 2% of total use Usage Pattern 4 flushes/pers/day 5 min./shower 2.5 min/pers/day 0.17 loads/pers/day 0.3 loads/pers/day N/A % Hot Water 0% 60% 50% 100% 25% 50%
How much energy we can save ?
Energy needed to treat water
Average energy use for water treatment drawn from southern California
studies is 652 kWh per acre-foot (AF), where one AF = 325,853 gallons.
Thermal Energy in Coal
The thermal power plants consume about 0.45 kg of coal per kWh.
Energy output/fire power plant
A typical 500 megawatt coal power plant produces 3.5 billion kWh per year.
CO₂ Emission
Taking coal to contain 50 percent carbon, which combines with oxygen during
burning to form CO₂, we can arrive at 1.83 kg CO₂ for every 1 kg of coal
burned.
Transcribed Image Text:How much energy we can save ? Energy needed to treat water Average energy use for water treatment drawn from southern California studies is 652 kWh per acre-foot (AF), where one AF = 325,853 gallons. Thermal Energy in Coal The thermal power plants consume about 0.45 kg of coal per kWh. Energy output/fire power plant A typical 500 megawatt coal power plant produces 3.5 billion kWh per year. CO₂ Emission Taking coal to contain 50 percent carbon, which combines with oxygen during burning to form CO₂, we can arrive at 1.83 kg CO₂ for every 1 kg of coal burned.
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